Overhaul Suggestions

155Assault · Sep 17, 2014

I am overhauling my 2011 Orange assault. I had intentions of doing an 858 kit. We disassembled the engine @ 4,000 miles, and my dealer said it looked like a 1500 mile engine. All it really needed was rings. No cracks, no scratches, Nothing wrong. Not only was I surprised, but even a little disappointed. Anyway on to the rebuild. After figuring the cost of everything, The 858 went by the way side. As of now we are installing the AXYS crank shaft, installing VR3 reeds, an RKT drop in kit with head. Kelsy didn't recommend using the new Axys crank, I believe he point was that I may lose torque with the lighter crank.
I am installing the new track I took off of my 14 Pro, changing every bearing and bushing, installing orange Burandt boards, and rebuilding the shocks, and considering new springs.
I am going with a new chain and gears. I am thinking about going 1 step higher gears, thinking more track speed with the faster revving engine would be a good thing. However I haven't really decided on that or clutching, and would like any recommendations, or let me know anything things I have overlooked. I appreciate the opinions.
The sled is an Assault and I use it as an all around sled and usually hammer it pretty hard.

simnil · Sep 17, 2014

I would like to se the calculations that shows torque loss due to a lighter crank! The crank itself doesn't produce torque, the combustion of fuel does.

Weight is good for one thing, not loosing speed when passing through something solid.

rmscustom · Sep 17, 2014

simnil said:
I would like to se the calculations that shows torque loss due to a lighter crank! The crank itself doesn't produce torque, the combustion of fuel does.

Weight is good for one thing, not loosing speed when passing through something solid.

With that logic wouldn't a heavier crank maintain speed better once its there?

Idcatman3 · Sep 17, 2014

rmscustom said:
With that logic wouldn't a heavier crank maintain speed better once its there?

It certainly would. The question is whether that's a good thing? Inertia works both ways, it will keep going easier, but it is harder to get it to change speed.

155Assault · Sep 17, 2014

Gearing

Does anyone have any further thoughts on the gearing? With the RKT kit design RPM increases to 8400, I am thinking with the HP Increase of the mods (maybe 15hp?) that and a stock track that track speed is the way to go, but I don't want to over do it....

simnil · Sep 17, 2014

rmscustom said:
With that logic wouldn't a heavier crank maintain speed better once its there?

What you want from a sled engine is rapid response, thus you need a light crank. (unless the engine design guy messed up and need the weight to dampen out vibrations)
If you loose rpms when hitting a bump or going from hard to loose snow that is a clutching problem.

On 50s diesel 35hp 3cyl farming tractors, w manual transmission, found around here they used an 80kg fly wheel to store as much of the little energy available to when it was needed. The backside of that is it takes 15 seconds to reach top revs.

Oh, another thing. A couple of years ago, I'm getting old so its probably 10-15, the Ford World rally team was disqualified from a WRC race for running a fly wheel that was 40 grams to light. Do you seriously think that they would go that near the limit of what was legal if they had nothing to gain?

Light is good, heavy is bad..... if only I could remember that when eating.....

wfieldin · Sep 18, 2014

I think that crank combination is going to be the go to upgrade for us older pro guys

TARI · Sep 18, 2014

The lightweight crankshaft works good, quicker acceleration, now it is similar to skidoo and cats lightweight cranks. terra alps offers lightweight cranks and machining.
also for bigbores an 858? and others using a 87mm piston is 831cc's, so gaining 5-10 hp with little porting? not worth it. could do some real porting on a 800 and do better then that or get a real 860 bigbore.

TRS · Sep 18, 2014

TARI said:
The lightweight crankshaft works good, quicker acceleration, now it is similar to skidoo and cats lightweight cranks. terra alps offers lightweight cranks and machining.
also for bigbores an 858? and others using a 87mm piston is 831cc's, so gaining 5-10 hp with little porting? not worth it. could do some real porting on a 800 and do better then that or get a real 860 bigbore.

Ted, what is your turn around time on a big bore?

pinko · Sep 19, 2014

TRS said:
Ted, what is your turn around time on a big bore?

Do some research on Terra....

damx · Sep 19, 2014

Not sure about terra alps pro big boar. But seen there cat BB, last winter,and it was impressive. The owner was happy with it. And had nothing but good things to say.

The450kid · Sep 19, 2014

damx said:
Not sure about terra alps pro big boar. But seen there cat BB, last winter,and it was impressive. The owner was happy with it. And had nothing but good things to say.

That's cause he is a salesman lol!

damx · Sep 19, 2014

This was not on terra own sled. On someone who bought there kit. IV seen the bad posts about them, but you never here the good. Most people only post the bad. Not to much about the good products. Not just about terra, but about any aftermarket company. Just my 2c.

Trenchmaster · Sep 20, 2014

Sounds like an interesting rebuild hope It works well, Looking forward to hearing more

155Assault · Sep 21, 2014

Gearing

Any thoughts on Gearing? up, Down, Leave it alone?

let me know what you think, I appreciate it.

McFarckle · Sep 22, 2014

If im correct, the crank out of the axys will not work. if you want to put a light crank in your 800 the axys crank is not the one. you want the crank out of a 2014 600RR (snowcross sled)

rmscustom · Sep 22, 2014

155Assault said:
Any thoughts on Gearing? up, Down, Leave it alone?

let me know what you think, I appreciate it.

Gear down not up on a mountain sled. Stock is way too high.

SwedenPro · Sep 22, 2014

Gear down, you got the extra revs to maintain speed, and get a snappier response, and if the torque question has any effect, you'll compensate that with the lower gearing....

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155Assault · Sep 24, 2014

Gearing

Thanks, I disassembling the chassis next week. I will look into the assault vs pro ratio, and probably gear down 1, and I will check on the crank. My dealer has done one before, and I had him order the crank, reed and RKT drop in kit. Will ask which crank we are putting in.

Overhaul Suggestions

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